With this patch, TX/RX CCIDs can now be changed on a per-connection basis, which

overrides the defaults set by the global sysctl variables for TX/RX CCIDs.
To make full use of this facility, the remaining patches of this patch set are

needed, which track dependencies and activate negotiated feature values.
Signed-off-by: Gerrit Renker

Acked-by: Ian McDonald

---

 Documentation/networking/dccp.txt |   14 ++++++++++++++

 include/linux/dccp.h              |    5 +++++

 net/dccp/proto.c                  |   32 ++++++++++++++++++++++++++++++++

 3 files changed, 51 insertions(+), 0 deletions(-)
--- a/Documentation/networking/dccp.txt

+++ b/Documentation/networking/dccp.txt

@@ -61,6 +61,20 @@ DCCP_SOCKOPT_AVAILABLE_CCIDS is also read-only and returns the list of CCIDs

 supported by the endpoint (see include/linux/dccp.h for symbolic constants).

 The caller needs to provide a sufficiently large (> 2) array of type uint8_t.
+DCCP_SOCKOPT_CCID is write-only and sets both the TX and RX CCIDs at the same

+time, combining the operation of the next two socket options. This option is

+preferrable over the latter two, since often applications will use the same

+type of CCID for both directions; and mixed use of CCIDs is not currently well

+understood. This socket option takes as argument at least one uint8_t value, or

+an array of uint8_t values, which must match available CCIDS (see above). CCIDs

+must be registered on the socket before calling connect() or listen().

+

+DCCP_SOCKOPT_TX_CCID is read/write. It returns the current CCID (if set) or sets

+the preference list for the TX CCID, using the same format as DCCP_SOCKOPT_CCID.

+Please note that the getsockopt argument type here is `int', not uint8_t.

+

+DCCP_SOCKOPT_RX_CCID is analogous to DCCP_SOCKOPT_TX_CCID, but for the RX CCID.

+

 DCCP_SOCKOPT_SERVER_TIMEWAIT enables the server (listening socket) to hold

 timewait state when closing the connection (RFC 4340, 8.3). The usual case is

 that the closing server sends a CloseReq, whereupon the client holds timewait

--- a/include/linux/dccp.h

+++ b/include/linux/dccp.h

@@ -203,11 +203,16 @@ enum dccp_feature_numbers {

 #define DCCP_SOCKOPT_SEND_CSCOV		10

 #define DCCP_SOCKOPT_RECV_CSCOV		11

 #define DCCP_SOCKOPT_AVAILABLE_CCIDS	12

+#define DCCP_SOCKOPT_CCID		13

+#define DCCP_SOCKOPT_TX_CCID		14

+#define DCCP_SOCKOPT_RX_CCID		15

 #define DCCP_SOCKOPT_CCID_RX_INFO	128

 #define DCCP_SOCKOPT_CCID_TX_INFO	192
 /* maximum number of services provided on the same listening port */

 #define DCCP_SERVICE_LIST_MAX_LEN      32

+/* maximum number of CCID preferences that can be registered at one time */

+#define DCCP_CCID_LIST_MAX_LEN	       16
 #ifdef __KERNEL__
--- a/net/dccp/proto.c

+++ b/net/dccp/proto.c

@@ -505,6 +505,34 @@ static int dccp_setsockopt_cscov(struct sock *sk, int cscov, bool rx)

 	return rc;

 }
+static int dccp_setsockopt_ccid(struct sock *sk, int type,

+				char __user *optval, int optlen)

+{

+	u8 *val;

+	int rc = 0;

+

+	if (optlen < 1 || optlen > DCCP_CCID_LIST_MAX_LEN)

+		return -EINVAL;

+

+	val = kmalloc(optlen, GFP_KERNEL);

+	if (val == NULL)

+		return -ENOMEM;

+

+	if (copy_from_user(val, optval, optlen))

+		rc = -EFAULT;

+

+	lock_sock(sk);

+	if (!rc && (type == DCCP_SOCKOPT_TX_CCID || type == DCCP_SOCKOPT_CCID))

+		rc = dccp_feat_register_sp(sk, DCCPF_CCID, 1, val, optlen);

+

+	if (!rc && (type == DCCP_SOCKOPT_RX_CCID || type == DCCP_SOCKOPT_CCID))

+		rc = dccp_feat_register_sp(sk, DCCPF_CCID, 0, val, optlen);

+	release_sock(sk);

+

+	kfree(val);

+	return rc;

+}

+

 static int do_dccp_setsockopt(struct sock *sk, int level, int optname,

 		char __user *optval, int optlen)

 {

@@ -519,6 +547,10 @@ static int do_dccp_setsockopt(struct sock *sk, int level, int optname,

 	case DCCP_SOCKOPT_CHANGE_R:

 		DCCP_WARN("sockopt(CHANGE_L/R) is deprecated: fix your app\n");

 		return 0;

+	case DCCP_SOCKOPT_CCID:

+	case DCCP_SOCKOPT_RX_CCID:

+	case DCCP_SOCKOPT_TX_CCID:

+		return dccp_setsockopt_ccid(sk, optname, optval, optlen);

 	default:

 		if (optlen < sizeof(int))

 			return -EINVAL;

--

1.6.0.rc2
--

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